Phage treatment significantly reduces Salmonella shedding in layer hens and Salmonella abundance on the surface of the eggs they produce

Non-typhoidal Salmonella species cause 85% of human foodborne cases and infections caused by multidrug-resistant Salmonella strains are increasing. Therefore, alternative antimicrobials are needed, and phage therapy offers a promising tool to reduce the spread of Salmonella in the human food chain. The aim of this study was to determine if a phage cocktail delivered in water could reduce Salmonella shedding in infected egg laying hens, and Salmonella abundance on the surface of eggshells in eggs produced by infected hens. 240 56-week-old layer hens, which were environmentally infected with Salmonella were divided into three treatment groups: T1, no phage cocktail, T2, phage cocktail at dose 3×10⁶ PFU/day and T3, phage cocktail at dose 3×10⁵ PFU/day. The phage cocktail was delivered in their drinking water, for 28 days. Our study found by day 28 the higher phage dose (T2) was more efficient at reducing Salmonella shedding (p<0.01) and median Salmonella shedding counts were 3.10×10⁴ and 0.00 CFU/g for groups T1 and T2 respectively. In the eggs produced by T2 phage treated hens, Salmonella abundance on eggshells was reduced by 60% (p<0.01) compared to the eggs produced by infected hens that received no phage treatment. We showed phage treatment effectively reduced Salmonella transmission in laying hens and in their eggs. Our data highlights that phage treatment is a promising tool to improve food safety.